Laws of Motion · Question 38

A car of mass m is moving on a level circular track of radius R. If s represents the coefficient of static friction between the road and tyres of the car, the maximum speed of the car in circular motion is given by

1. s mRg
2. Rg s
3. mRg s
4. s Rg

A car of mass 1000 kg negotiates a banked curve of radius 90 m on a frictionless road. If the banking angle is 45 , the speed of the car is

1. 20 m s-1
2. 30 m s-1
3. 5 m s-1
4. 10 m s-1

A conveyor belt is moving at a constant speed of 2 m s-1. A box is gently dropped on it. The coefficient of friction between them is = 0.5. The distance that the box will move relative to belt before coming to rest on it, taking g = 10 m s-2, is

1. 0.4 m
2. 1.2 m
3. 0.6 m
4. zero

A person of mass 60 kg is inside a lift of mass 940 kg and presses the button on control panel. The lift starts moving upwards with an acceleration 1.0 m/s2. If g = 10 m s-2, the tension in the supporting cable is

1. 8600 N
2. 9680 N
3. 11000 N
4. 1200 N

A body of mass M hits normally a rigid wall with velocity V and bounces back with the same velocity. The impulse experienced by the body is

1. MV
2. 1.5 MV
3. 2MV
4. zero

A block of mass m is in contact with the cart C as shown in the figure. The coefficient of static friction between the block and the cart is . The acceleration of the cart that will prevent the block from falling satisfies [figure]

1. > mg
2. > g m
3. g
4. < g

A gramophone record is revolving with an angular velocity . A coin is placed at a distance r from the centre of the record. The static coefficient of friction is . The coin will revolve with the record if

1. r = 2
2. r < 2
3. r 2
4. r 2

A man of 50 kg mass is standing in a gravity free space at a height of 10 m above the floor. He throws a stone of 0.5 kg mass downwards with a speed 2 m/s. When the stone reaches the floor, the distance of the man above the floor will be

1. 9.9 m
2. 10.1 m
3. 10 m
4. 20 m

The mass of a lift is 2000 kg. When the tension in the supporting cable is 28000 N, then its acceleration is:

1. 4 m s-2 upwards
2. 4 m s-2 downwards
3. 14 m s-2 upwards
4. 30 m s-2 downwards

A body, under the action of a force F = 6 i - 8 j + 10 k, acquires an acceleration of 1 m s-2. The mass of this body must be

1. 10 kg
2. 20 kg
3. 10 2 kg
4. 2 10 kg